The present invention relates to wireless communications in general and, in particular, to the adjustment of modulation and coding for satellite downlinks.
Remote sensors are often placed on low earth orbit (LEO) satellites to gather information about earth, weather, and space. Many remote sensors gather information by sensing different wavelengths of electromagnetic waves emitted from an object of interest. One common use is satellite imaging to map, measure, or otherwise monitor the earth. Other remote sensing systems may measure sounds, or variations in magnetic or gravitational fields. Remote sensing satellites are typically in low earth orbit, and often transmit the data gathered with the remote sensors to ground terminals at locations on earth.
These transmissions may be bandwidth limited, and often operate within a 400 MHz bandwidth in the X-band. This can present a limitation on the amount of data that may be transmitted to the ground terminals. Other types of satellite transmissions (e.g., with other types of sensors) may have similar bandwidth limitations. It may, therefore, be desirable to identify novel methods that may be used to improve the bandwidth efficiency of a system for data transmission in a downlink of a communications satellite.